1. Field of the Invention
The present invention relates in general to equipment for grinding/polishing a curved or flat wall element.
2. Description of the Related Art
It has previously been quite difficult, if at all possible, to very precisely and reliably grind or polish a structure having a curved surface, especially in the field. An example of such a curved structure is an aircraft cabin window, which needs to have micro cracks and other damage removed with a grinding/polishing procedure every two to four years. Aircraft cabin windows are especially difficult to grind/polish because the windows are made of stretched acrylics, which is a very heat sensitive material. Also, since the aircraft cabin windows are often curved along a single axis, special requirements are placed on the precision and geometry when grinding/polishing the surface thereof.
What is needed in the art is a device capable of precisely and reliably grinding or polishing a structure having a curved surface, especially while the structure is in the field.
The present invention provides a grinding tool attached to a frame which allows the grinding tool to follow the curvature of a surface to be polished by the grinding tool.
The invention comprises, in one form thereof, an apparatus for grinding and/or polishing a surface of a wall element. The apparatus includes a first elongate guide device oriented substantially parallel to the surface of the wall element. A second elongate guide device is movably coupled to the first elongate guide device and oriented orthogonally relative thereto. The second elongate guide device is oriented substantially parallel to the surface of the wall element and moves along the first elongate guide device. A polishing device is movably coupled to the second elongate guide device. The polishing device moves along the second guide device and polishes the surface of the wall element at a plurality of locations along the second guide device and along the first guide device.
The present invention suggests equipment which makes possible grinding or polishing of a curved wall element. A machine is provided having four degrees of freedom (x, y, z and one rotation). The machine has a grinding/polishing tool which can follow the surface of a cabin window having a single curvature. The tool maintains a well defined line contact throughout its movement over the curved surface. Water or any other coolant could be applied for additional cooling of the workplace.
The invention includes a frame with devices mounted thereon for fixing the frame to the wall element; first rectilinear, parallel guide devices fixed in the frame for guiding a respective support device of a carriage displaceably mounted in the frame in a first linear direction, the support devices having slide or roller elements intended to be in contact with a track mounted on and having the same curvature as the surface of the wall element and facilitating the movement of the carriage thereon in the first linear direction; second rectilinear, parallel guide devices connecting respective support devices to each other; a slide which is displaceably mounted on the second guide devices in a second linear direction substantially perpendicular to the first linear direction, the slide being disposed to carry a tool unit for grinding or polishing the wall element; a guide slide which is displaceably mounted on cooperating first guide devices and which is joined to a respective support device in such a manner that the support device is, firstly, pivotally mounted relative to the guide slide about a pivot axis parallel to the second guide devices, and, secondly, is displaceably mounted relative to the guide slide in a direction normal to the surface of the wall element carrying the track against which the slide or roller elements of the support devices are intended to be in contact; and devices arranged to bias each support device with its slide or roller element against the track. Such an arrangement makes it possible to anchor the frame in such a manner over the section of the wall element to be polished that the carriage and the tool unit carried thereon can be made to follow the curvature of the wall element with the operating axis of the tool unit always oriented parallel to the surface of the curved wall element.
The equipment is preferably so dimensioned and designed so as to be portable and suitable for use for polishing/grinding when the window is still mounted in the aircraft. The equipment can also be used for polishing of a window when the window is dismounted from the aircraft. The carriage and the slide with the tool unit mounted thereon can thus be manually operated or operated by servomotors which are computer controlled (not shown in the Figures). By virtue of the fact that the frame can be fixed to a wall element in any plane orientation, or arranged to follow a track with the wall curvature, the operator does not need to carry any portion of the weight of the equipment when it is being used.
The frame itself of the above-described equipment needs to have its fixing devices mounted on a surface having substantially the same curvature profile as the wall element to be ground or polished. This is not necessary, however, in the case when the roller elements are arranged to follow a curved track which follows the curvature of the wall element.
An advantage of the present invention is that an aircraft cabin window can be polished while the window is still mounted in the aircraft.
Another advantage is that a structure having a curved surface can be polished.